The invention relates to a process for the preparation of a proteinaceous concentrate. More particularly, the present invention relates to a process for the preparation of protein concentrates by the aerobic cultivation of yeast on whey.
In the synthesis of microbial products, it has been conventional to utilize a nutrient medium comprising whey (the serum or watery part of milk), the dry matter content of which is typically 14% protein and 70% milk sugar. In light of its composition, whey is considered to be one of the most suitable nutrient media for obtaining biomass by fermentation.
To this end, it has been common to employ various continuous fermentation techniques wherein whey is fermented by use of yeast to yield a protein-rich product. Such processes typically involve (a) the enrichment of protein-poor whey with nitrogenous substances such as urea or ammonium salts, (b) the adjustment of pH with phosphoric acid, and (c) the addition of mineral constituents such as zinc or magnesium. The resultant nutrient medium is then fermented in the presence of oxygen until the lactose content is reduced to less than 1%, thereby yielding a product which typically evidences a dry matter content ranging from 4.0-4.5% and approximately 25 grams of dry yeast per liter. The product so prepared may then be densified or, in the alternative, dried.
Although such processes have been widely used in commercial applications, economic considerations have prompted workers in the art to seek out suitable alternatives. Additional limitations also obtain in the relatively low concentration of nutrients in whey prepared in the foregoing manner.